The adventurer Indiana Jones ventures deep into a dark and creepy cave, where he incredibly overcomes a series of dangerous traps to seize a golden idol, without realizing that in doing so, he has just set off a final trap that will chase him as he scrambles to exit the tunnel: an enormous stone ball rolling hot on his heels intent on crushing him as punishment for robbing the idol.

The first film from the “archeological” series featuring Harrison Ford opens with the enormous granite sphere, a phenomenon that has captured the interest of curious archeologists, science fiction writers and observers in general for over a thousand years.

In the region of the Diquis River Delta, on the Island of Caño, and in several other locations, a few hundred of these enigmatic stone balls (over 300 have been catalogued to date) sit in surprisingly spherical perfection, inspiring intriguing questions regarding their origin, history and function.

It seems that some 500 of these rock orbs exist, which range in diameter from just 10 cm. to two and a half meters. They are carved in black granite or granodiorite, a rock similar to granite, interestingly the same material used for the famous “Rosetta Stone”, used by archeologist Champollion to begin deciphering the Egyptian hieroglyphics.

These spheres, known locally as Bolas de Costa Rica (Costa Rican Balls), caught the attention of the Spanish conquistador Francisco Pizarro, who in 1547 stated that “the lords of this empire gather every four years in this Country of Balls, where they receive advice from great wise men”.

The geographic location of Costa Rica, in the center of Central America, is likely the reason that artifacts can be found here which display a variety of influences from the Mayans of the north to the Olmecs and the Toltecs of Mexico, the Chibchas of Colombia and even the Quechuas and Incas of distant Peru.

In 1939, as loggers from the U.S.’s Standard Fruit Company deforested the region to grow bananas, they discovered a number of these balls, some of which they blasted with dynamite in the hopes of finding gold. They didn’t find the precious metal, but they did stumble upon an enigma that remains a mystery. In 1943, the archeologist Doris Stone published in American Antiquity the first known article about the spheres. The piece caught the attention of S. Kirkland Lothrop of the University of Harvard, author of the reference book on rocks “archeology of the Diquis Delta”, published in 1963. Beginning in 1970, the Costa Rican government has protected the pre-Columbian spheres and some of the balls damaged by dynamite have even been reconstructed.

Today, these rock spheres make up part of this Central American country’s iconic landscape, and they are even present in some official buildings, town squares, and emblematic places in the capital city of San Jose. They even appear on the five thousand colon bill.

On March 1, 2013, UNESCO began the process of analyzing the phenomenon, and all Costa Ricans, including President Laura Chinchilla, hope that in 2014 the cultural organization will announce that they will be including the Balls of Costa Rica on their world heritage list.

We do not know the exact function of the balls. No logical explanation regarding their disposition and organization in relation to the earth has ever been found and precisely who created them is also unknown (although their appearance and the quality of craftsmanship they display seem to indicate one culture that has unfortunately been largely lost), and finally the time of their creation also remains unknown… The stone spheres sprinkled around Costa Rica have served as a source of inspiration for painters and sculptors and they have inspired creative theories from those that insist the balls were left by the last inhabitants of Atlantis. Swiss “scientific” writer Erik von Däniken says they provide clear evidence of a visit from ancestral extra-terrestrials.

What is clear is that, while other regions have pyramids, obelisks, and monuments such as Stonehenge, Costa Rica’s stone spheres also offer a rare glimpse into a distant and mysterious past.